Dna's Map Completed

How Genes Interact Still A Puzzle

Two competing teams of scientists proclaimed Monday they have completed rough drafts of the human genome--nature's blueprint for creating and sustaining life--after a 10-year, multibillion-dollar effort that has been called biology's version of the splitting of the atom. But cracking the human genetic code promises to change the future even more profoundly.

Assembling the catalog of the book of life is a staggering technical achievement that seems sure to change forever how we humans look at ourselves. But the word "future" should not be lost in all the hyperbole and excitement over the announcement.

Despite Monday's White House news conference, with President Clinton announcing "A day for the ages," what researchers now have is a string of 3 billion letters that must be read to learn where their patterns spell out genes. Scientists don't even know how many genes are among them. In a betting pool set up by one scientist recently, estimates ranged from 34,000 to 140,000.

According to the archive of genetics, the Online Mendelian Inheritance in Man, a total of 11,722 genes have been discovered and characterized thus far. That's an impressive number, but only a third of the minimum estimate. There's a long way to go.

Genes and the environment work together to shape who we are, and in the years ahead studying that interaction will be possible. A gene is a sequence of DNA that is a recipe for a single protein. These proteins join together by the thousands to build tissues, organs and finally whole organisms.

But the purpose of most of the genes in the human genome seems to be regulating the workings of the other genes.

The story gets complicated further because 97 percent of our genome does not consist of protein-coding genes at all. The genome is actually an archive of human evolution and consists of the preserved genes we share with other animal species--chimps, fruit flies, even common brewer's yeast. But also preserved is the detritus from millions of years--failed genes, dead genes, viral genes--all the strange entities called pseudogenes, retropseudogenes, satellites, minisatellites, microsatellites, transposons and retrotransposons--collectively referred to as "junk DNA."

All of it had to be sequenced, though, and the sequence is eventually expected to revolutionize knowledge of the human body (just one small aspect, DNA fingerprinting, comes out of junk DNA and already has revolutionized forensics) and to raise biotechnology to one of the century's major industries.

Finding the total sequence of all the DNA subunits in our cells means science can get to the next stage: Trying to find what it all means.

It is suspected that humans share 99.9 percent of their DNA, meaning that of the 3 billion letters in the genetic code, each of us differs by about 300,000. Those determine our individuality, our talents, and our susceptibility to diseases, among other things. Having the entire sequence and its relatively few variations will enable medical science to truly treat us as individuals.

Dr. Francis Collins, head of the Human Genome Project of the National Institutes of Health, said that having the sequence allows humans for the first time to read "our own instruction book. Today, we celebrate the revelation of the first draft of the human book of life."

Standing with the president and Collins was scientist-entrepreneur J. Craig Venter, whose upstart biotech company, Celera Genomics, of Rockville, Md., was widely viewed as having forced a last-minute truce with the government by having earlier announced it had completed the sequence and would be providing it to subscribers.

The truce includes the publication of both groups' versions of the genome at the same time in the same journal. But there is no reason to believe that a breakthrough has been achieved over the issue that wrecked previous conciliation efforts: access to the data.

President Clinton made the White House announcement, for which he was joined by British Prime Minister Tony Blair via satellite transmission.

Said Blair: "Let us be in no doubt about what we are witnessing today: A revolution in medical science whose implications far surpass even the discovery of antibiotics. [This is] the first great technological triumph of the 21st Century."

As it has from the beginning, a group of hundreds of government scientists from the U.S., Britain, France, Germany, Japan and China who have been working in 16 centers around the globe will keep downloading sequence data every 24 hours on the Internet site GenBank, where it is freely available to researchers. Celera has sought restrictions on access to preserve its interest in profiting from the data by interpreting it.

Computer technology has speeded up sequencing exponentially. For example, a major sequencing center produced 600 million letters last year. In comparison, Venter expects to produce more than a hundred million letters of the genetic code every 24 hours--he will be able to do in a week what recently took a year.